Method and apparatus for angle measurement or to define angular location of an object

ABSTRACT

The invention relates to a method and an apparatus for angle measurement or for the determination of an angle of position for an object. The method comprises the use of a beacon having a known position and rotating around its axis, which emits light or reflects light focused thereon. The light emitting from the beacon being determined either previously or for the start of each measurement for a given reference bearing. In the method, the light emitted from the beacon is picked up by a receiver present in an object to be measured, which is provided with elements for determining, by means of the light received from the beacon, the rotational speed of the beacon and further an angular position for the object with respect to said reference bearing. The method is further capable of measuring a distance by using a conventional know base with a receiver at each end, whereby the distance between an object to be measured and the beacon can be determined by working out the triangle or by measuring the peripheral speed between the receivers and by making use of the knowledge about the angular speed of the beacon.

The present invention relates to a method and an apparatus for anglemeasurement or for the determination of an angle of position for anobject.

An object of the present invention is to provide an improved measuringmethod and measuring apparatus, wherein the angle measurement functionsof a currently used theodolite or tacheometer can be replaced with anapparatus of a simpler technical design, which is moreover reliable inoperation and attractive in terms of its price. Another object of theinvention is to provide a method and an apparatus, wherein theperformance of a measuring process requires one person only.

In order to achieve the above objectives, a method of the invention ischaracterized in that the method comprises the use of a beacon having aknown position and rotating around its axis, which emits light orreflects light focused thereon, the light emitting from the beacon beingdetermined either previously or for the start of each measurement for agiven reference bearing, and in which method the light emitted from thebeacon is picked up by a receiver present in an object to be measured,which is provided with elements for determining, by means of the lightreceived from the beacon, the rotational speed of the beacon and furtheran angular position for the object with respect to said referencebearing. On the other hand, an apparatus of the invention ischaracterized in that the apparatus comprises a beacon rotating aroundits axis, which is placeable in a known position and which beacon isadapted to emit light or to reflect light focused thereon, the lightemitting from the beacon being determined either previously or for thestart of each measurement for a given reference bearing, and a receiverplaceable in an object to be measured, which is adapted to receive thelight emitted from the beacon, said receiver being provided withelements adapted to determine, by means of the light received from thebeacon, the rotational speed of the beacon and further an angularposition for the object with respect to said reference bearing.

The invention will now be described in more detail with reference to theaccompanying drawings, in which:

FIG. 1 shows schematically one exemplary embodiment for a beaconincluded in an apparatus of the invention,

FIG. 2 shows one exemplary embodiment for a receiver included in anapparatus of the invention, and

FIG. 3 shows schematically in a plan view the position of an object tobe measured relative to a reference bearing.

The embodiment shown in FIGS. 1 and 2 for an apparatus of the inventioncomprises a beacon 15 adapted to be rotatable around its vertical axisand provided with a balancing bed 1, upon which is mounted a housing 4,enclosing e.g. a motor, a gearshift, and necessary electronics. Abovethe housing is fitted a measuring rod 9, having its top end providedwith an antenna 10. In the depicted embodiment, the measuring rod 9 isprovided both in its lower section and its upper section with reflectingsurfaces 5, which are intended for an apomecometer included in areceiver 16. The vertical medial area in the reflecting surface 5 of thelower section is provided with a transparent zone 6, which is fittedwith the signal light of a null detector. This signal light is used toindicate a full revolution of the beacon and for a zero adjustment ofthe beacon in a given reference bearing R (FIG. 3), which can be fixed,e.g. a true north or some other predetermined fixed bearing, or whichreference bearing R can be re-determnined for the start of eachmeasurement. Alternatively, the antenna 10 can be used for transmittinga time signal about a reference bearing to the receiver by way of aradio. In addition, the lower reflecting surface has its outer faceprovided with a prismatic reflector 8 for the back-reflection of lightfocused on the beacon. Moreover, between the housing 4 and the balancingbed I is fitted a locking screw 2 for the beacon alignment as well as afine adjustment screw 3 for the beacon alignment. By means of thebalancing bed 1, the beacon can be set up in a precisely verticalposition.

In the depicted embodiment, the receiver 16 comprises a stand 11, havingits top end fitted with a schematically illustrated processor andgradometer 12, a light detector 13, as well as an alignment telescopeand apomecometer or telemeter 14.

In the illustrated embodiment, the beacon 15 is adapted to rotate aroundits vertical axis and to emit a light signal, e.g. a vertical line oflight, or to reflect light focused thereon. The beacon is set up in aknown position or its position can also be determined e.g. by means ofsatellites included in the GPS system, as the beacon is being erected orthereafter. The beacon can be installed fixedly in position, e.g. forthe duration of measurements required at a construction site, and thereference bearing R can also be determined to be fixed, e.g. a truenorth or some other known direction. The reference bearing can also bedetermined e.g. for the start of each measurement by positioning thereceiver 16 on another known spot, said receiver observing a lightsignal either emitted by the beacon or emitted by the receiver andreflected back by the beacon. A clock included in the receiver 16 and aprocessor 12 can use a light signal emitted by the beacon 15 orreflected by the beacon for calculating the rotational speed of thebeacon, said rotational speed being converted into desired angularunits. The rotational schedule of the beacon, turned into angular units,is then brought to match the angular reading of a known beacon-receiverdirection, whereby the receiver can be synchronized with the time of theangular schedule of the beacon. Thereafter, as the receiver 16 isdirected to the beacon 15 from any spot to be measured, the light signalemitted or reflected by the beacon uses the clock of the receiver 16 toprovide an angular reading which corresponds to the directionbeacon-object to be measured (indicated by the letter M in FIG. 3). Theapomecometer 14 and the gradometer 12 included in the receiver can beused for measuring the distance and the angle of altitude of an objectto be measured with respect to the beacon. Taking into account a bearingmeasured from the beacon and the height of the beacon, it is possible tocalculate x-, y- and z-coordinates for the object to be measured. Theuse of a receiver provided with a conventional base and two detectorsprovides a solution, wherein the distance can be determined by workingout the triangle or by measuring the peripheral speed between thedetectors which, together with the known rotational speed of the beacon,provides the desired distance information. The measurement for adifference in altitude can also be performed as a distance measurementby fitting the beacon with a vertically set measuring rod 9, thedistance between the lower and upper reflectors 5 or measuring marksmounted thereon being the dimension necessary for working out thetriangle.

FIG. 3 illustrates schematically an implementation of the method. Thebeacon 15 is first determined for a given reference bearing R, which maybe e.g. a true north, whereby, as the beacon 15 is rotating, thereceiver 16 present in an object to be measured is informed about amoment the null detector is coincident with the reference bearing R.Such information can be transmitted to the receiver 16 either as a lightsignal (as a null detector signal light 7) or a radio signal (theantenna 10). The receiver 16 picks up the light coming from the beacon15 (either emitted by the beacon or emitted by the receiver andreflected by the beacon) in a direction M, the receiver 16 using itsclock and microprocessor to work out the rotational speed of the beacon15 and to convert the same into desired angular units. A thus determinedangular schedule for the beacon can be used for measuring an angularposition a for an object to be measured with respect to the referencebearing R in a comparatively simple fashion by means of a measurement oftime.

In addition to the above-referred construction site, the method andapparatus of the invention can be used in variety of specialapplications, e.g. in the survey of power lines and in otherapplications that require accurate angular/directional measurement. Themethod is also conceivable for use in connection of level lasers byusing a rotating level laser as a beacon.

The apparatus and method of the invention can also be implemented insuch a way that the beacon is adapted to rotate around something otherthan a vertical axis, the angle of position of an object beingmeasurable at different levels perpendicular to said axis of rotation;for example, by adapting the beacon to rotate around a horizontal axisand by using e.g. a horizon level as the reference bearing, the angle ofposition can be measured in a vertical plane directly by means of alight detector included in the beacon and the receiver without aseparate gradometer for an angle of altitude.

What is claimed is:
 1. A method for effecting an angle measurement orfor the determination of an angle of position for an object,characterized in that the method comprises the use of a single beaconhaving a known position and rotating around its axis, which emits asingle beam of light, the light emitting from the beacon beingdetermined either previously or for the start of each measurement for agiven reference bearing (R), and in which method the light emitted fromthe beacon is picked up by a receiver present in an object to bemeasured, which is provided with elements for determining, by means ofthe light received from the beacon, the current rotational speed of thebeacon, and in which method the receiver is supplied with informationabout a moment the beacon is coincident with the reference bearing andabout a moment the receiver picks up the light emitted from the beacon,whereby the difference between said moments and said rotational speed ofthe beacon can be used for determining the angular position for thereceiver present in an object with respect to the reference bearing. 2.A method as set forth in claim 1, characterized in that the beacon isinstalled in the method fixedly in a given position and the referencebearing is determined fixedly in a given direction.
 3. A method as setforth in claim 2, characterized in that the beacon (15) is adapted torotate around its axis and that the fixed reference bearing comprises ahorizon level or some other reference plane.
 4. A method as set forth inclaim 3, characterized in that the beacon (15) is adapted to rotatearound its vertical axis and that the fixed reference bearing comprisesa true north.
 5. A method as set forth in claim 4, characterized in thatthe method comprises the use of an apomecometer (14) for thedetermination of site coordinates for an object.
 6. A method as setforth in claim 4, characterized in that the method comprises the use ofa conventional base with a receiver at each end, whereby the distancebetween an object to be measured and the beacon can be determined byworking out the triangle or by measuring the peripheral speed betweenthe receivers and by making use of the knowledge about the angular speedof the beacon.
 7. A method as set forth in claim 4, characterized inthat the beacon (15) is adapted to rotate around its vertical axis andthat the method further comprises the use of a gradometer (12) mountedon the receiver for the determination of vertical coordinates for anobject.
 8. An apparatus for the determination of an angle of positionfor an object, characterized in that the apparatus comprises a beaconrotating around its axis, which is placeable in a known position andwhich beacon is adapted to emit a single beam of light, the lightemitting from the beacon being determined either previously or for thestart of each measurement for a given reference bearing, and a receiverplaceable in an object to be measured, which is adapted to receive thelight emitted from the beacon, said receiver being provided withelements adapted to determine, by means of the light received from thebeacon, the current rotational speed of the beacon and further anangular position (α) for the object with respect to said referencebearing.
 9. An apparatus as set forth in claim 8, characterized in thatsaid elements of the receiver (16) include a light detector (13), aclock, and a microprocessor (12).
 10. An apparatus as set forth in claim9, characterized in that said elements of the receiver (16) furtherinclude an apomecometer (14) and a gradometer (12) for an angle ofaltitude.
 11. A method as set forth in claim 10, characterized in thatthe beacon is adapted to rotate around its axis and that the fixedreference bearing comprises a horizon level or some other referenceplane.
 12. A method as set forth in claim 11, characterized in that thebeacon is adapted to rotate around its vertical axis and that the fixedreference bearing comprises a true north.
 13. A method as set forth inclaim 12, characterized in that the method comprises the use of anapomecometer for the determination of site coordinates for an object.14. A method as set forth in a claim 12, characterized in that themethod comprises the use of a conventional base with a receiver at eachend, whereby the distance between an object to be measured and thebeacon can be determined by working out the triangle or be measuring theperipheral speed between the receivers and by making use of theknowledge about the angular speed of the beacon.
 15. A method as setforth in claim 12, characterized in that the beacon is adapted to rotatearound its vertical axis and that the method further compris4s the useof a gradometer mounted on the receiver for the determination ofvertical coordinates for an object.
 16. A method as set forth in claim1, characterized in that the method comprises the use of an apomecometerfor the determination of site coordinates for an object.
 17. A method asset forth in a claim 1, characterized in that the method comprises theuse of a conventional base with a receiver at each end, whereby thedistance between an object to be measured and the beacon can bedetermined by working out the triangle or be measuring the peripheralspeed between the receivers and by making use of the knowledge about theangular speed of the beacon.
 18. A method as set forth in claim 1,characterized in that the beacon is adapted to rotate around itsvertical axis and that the method further comprises the use of agradometer mounted on the receiver for the determination of verticalcoordinates for an object.